The present invention relates to a cooling system for a water cooling type engine having both an improved heating characteristic upon starting a cold automobile engine and a function for preventing icing of a throttle body.
In general, the cooling system of a water cooling type engine is constructed, as shown in FIG. 3, to cool the engine 100 by circulating cooling water by means of a pumping operation of a water pump 104 mounted to the inlet side of a water jacket 103 formed with a cylinder block 101 and a cylinder head 102 of an engine 100. Since the cooling water circulating in the water jacket 103 is not heated to a predetermined temperature (approximately 80.degree. C.) when initially starting the engine, a thermostat 106 in a water temperature controlling device 105 induces the flow of cooling water to a throttle body 107 and a heater core 108 so as to preheat the throttle body and the heater core. After a predetermined time elapses from the starting of the engine, the cooling water becomes heated to the predetermined temperature, and the thermostat 106 causes the cooling water to flow to a radiator 109 so that the heated cooling water is cooled by a heat exchanging operation and recirculated to the engine.
However, with the conventional technique, since the preheating of the throttle body and heater core depends on the heat source of the cooling water, the preheating effect, when the engine is cold, cannot be achieved because the cooling water is not heated. Since the throttle body is not preheated when the engine is started, cold air is supplied to the engine, which causes deterioration of combustion efficiency and lowers the heating characteristic. These problems are greatest in severe cold seasons.